2: The Basics of Provable Security
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- Oct 30, 2022
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Edgar Allan Poe was not only an author, but also a cryptography enthusiast. He once wrote, in a discussion on the state of the art in cryptography: { }^{1}
"Human ingenuity cannot concoct a cipher which human ingenuity cannot resolve."
This was an accurate assessment of the cryptography that existed in 1841 . Whenever someone would come up with an encryption method, someone else would inevitably find a way to break it, and the cat-and-mouse game would repeat again and again.
Modern 21st-century cryptography, however, is different. This book will introduce you to many schemes whose security we can prove in a very specific sense. The codemakers can win against the code-breakers.
It’s only possible to prove things about security by having formal definitions of what it means to be "secure." This chapter is about the fundamental skills that revolve around security definitions: how to write them, how to understand & interpret them, how to prove security using the hybrid technique, and how to demonstrate insecurity using attacks against the security definition.
{ }^{1} Edgar Allan Poe, "A Few Words on Secret Writing," Graham’s Magazine, July 1841, v19.
